From a solid sphere of mass M and radius R, a spherical portion of radius R/2 is removed, as shown in the figure Taking gravitational potential `V =0at r = oo,` the potential at (G = gravitational constatn)
A. `(2-GM)/(3R)`
B. `(-2GM)/(R)`
C. `(-GM)/(2R)`
D. `(-GM)/(R)`